The Basics: Building a Raised Garden Bed

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For the soil- and drainage-poor gardener, a raised garden bed offers the opportunity to perfect your environment and control many of the factors that are otherwise left up to nature. Building a raised garden bed allows you to optimize soil nutrients and drainage, even as you prevent soil erosion and save your back from added strain during weeding and harvesting.

The first step to building a raised bed is choosing a location that fits the needs of whatever you choose to grow—usually a spot that receives full sun, about six to eight hours. And while a bed can correct poor drainage, don’t set it in a marshy area. Many materials can form your framing, depending on how much you choose to spend. On the inexpensive side, concrete blocks work well, as does pressure-treated lumber, usually cedar. Pricier decorative stone or brick work well, too.

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If using lumber, build the frame with posts that that can stabilize in the ground, or create a trench at least a few inches deep. Lay out the plot no more than three or four feet wide, keeping in mind that you need to be able to reach all the plants to harvest or water. The raised garden bed should be about a foot deep, although for plants with deep roots, go up to 18 inches. (When using any kind of treated wood to build a bed for edibles, be sure to line the lumber so as to prevent it from leaching toxins into the soil.)

For ambitious gardeners, installing an irrigation system can make the raised bed even lower-maintenance—microsprinklers or soaker hose systems work best and don’t wet the foliage (which can cause mold). Put an irrigation system in place before adding soil to the bed, or just rely on hand-watering through the dry season.

Fill the bed with a sandy clay loam soil that’s been well-mixed with compost or other organic matter. After planting, you can add mulch (try pine straw or mini pine bark nuggets) as the finishing touch, an especially important one to raised beds, which can be prone to drying out.

Succession planting for crops allows for the most efficient use of your new space and simply means planning the layout of the bed so that all the plants that harvest at the same time can be replaced.

For an raised garden bed that’s ornamental—to be planted with flowers and other beautiful plants—aesthetics are of course the most important consideration in plant selection and layout. Trellises and stakes will help conserve space, as plants climb instead of sprawl. Once you’re ready to plant, add seedlings of various varieties and next year, you’ll have a bonus: The soil in raised garden beds heats up faster than the rest of the landscape, so you get on average a two-week head start in planting.